The present invention relates to a device for holding and storing at least two distinct spoolable pipes.
In the offshore oil industry, various types of pipes are used, including flexible pipes for transporting fluids such as liquid or gaseous hydrocarbons, water or air. The flexible pipes generally connect one or more items of surface equipment to one or more items of sea-bed equipment such as a production well or a manifold, part of the flexible pipes lying on the sea bed. The structure of these flexible pipes is well known and described, for example, in FR-A-2 553 859.
The operations of laying and/or testing the flexible pipes or certain other operations employing remote-controlled means such as underwater vehicles known as ROVs (Remote Operated Vehicles) require the use of other pipes which may be of the flexible pipe type, the structure of which is similar to that of the flexible production pipes which are used for abandonment and/or for recovering the main pipes, or of the umbilical type which is also well known to specialists in this field. The various structures of the pipes in use in the oil industry are, for example, described and referenced in the various API (American Petroleum Institute) publications.
The operations of laying a flexible pipe have sometimes to be broken off as a matter of urgency, for example in the event of fierce storms. This interruption is performed using either a winch paying out a steel cable which is connected to the flexible pipe, so as to set down on the sea bed one end of a portion of the flexible pipe which was in the depositing phase, or a secondary pipe of the flexible pipe type, as is described in FR-A-2 056 428.
At all events, the surface equipment such as a laying vessel comprises different holding and storage means, some of these means being associated with the main flexible production pipe, and others being associated with the secondary pipes as opposed to the main flexible pipe. Now, for medium and great depths of between 1000 and 2500 m, and even more, the means for holding and storing the main and secondary pipes have to be of very large size. For long lengths of main flexible pipe, baskets are generally used and are similar to the one depicted in the drawings of U.S. Pat. Nos. 3,804,111 and 3,941,146. Such baskets have an outside diameter of between 10 and 15 m. The secondary pipes such as an abandonment flexible pipe, like the one depicted in FR 2056428, are spooled onto reels, the payload of which is restricted to 250-300 tonnes, which corresponds to a length of secondary pipe of between 1500 and 2000 m.
It is quite clear that such storage means, baskets and/or reels, take up a very great deal of space on the deck of a laying vessel, thus restricting the amount of space available for the manoeuvres which are essential to laying, tests and/or recovering a main flexible pipe or alternatively for storing other equipment. In addition, there is no need to remind the reader that the longer the lengths of main flexible pipe and secondary pipe, the larger and more numerous the storage means will be.
In certain cases, the capacity of the baskets allows the storage either of a very great length of flexible pipe or several different pipes of different lengths and diameters. When this is the case, the basket is filled according to the sequence in which the pipes will be laid. Thus, the first pipe loaded into the bottom of the basket will be the last to be laid, whereas the last pipe loaded into the basket will be the first to be laid. When use is made of an abandonment and recovery pipe which needs to be used on any pipe that is to be laid, it cannot be stored in the basket containing the various pipes and has therefore to be stored on an independent reel.
The object of the present invention is to provide a device which makes it possible to hold and store at least one main pipe and one secondary pipe on one and the same means, so as to reduce the amount of space occupied by this storage means on the deck of the laying vessel or of another equivalent surface structure from which the said pipes are handled.
The subject of the present invention is a device for holding and storing at least two distinct spoolable pipes, one of which consists of a main first flexible pipe used in offshore oil operations, the said device comprising a first cylindrical structure and a second cylindrical structure with different diameters, the main first flexible pipe being held and stored in a first cylindrical structure, the two cylindrical structures being concentric, able to rotate about an approximately vertical axis of rotation and having an upper face which is open and a lower face which is closed by an end plate, and means for rotating the said cylindrical structures, and it is characterized in that the secondary second pipe is arranged in the second cylindrical structure which comprises three distinct and concentric housings, the two end housings, namely the innermost housing and the outermost housing, being for holding and storing the said secondary second pipe, the central housing constituting a transition zone for the passage of the said secondary pipe between the innermost and outermost housings.
One advantage of the present invention lies in the fact that it is possible to hold and store two pipes of different, similar, analogous or identical structures in one same device such as a basket, of a size which is smaller than was the case in installations of the prior art. In addition, it is possible to coil and uncoil the pipes stored in the corresponding cylindrical structures independently of each other.
According to another feature of the present invention, the central housing comprises a member for supporting and guiding the secondary second pipe as it passes between the upper end of one end housing to the lower end of the other end housing.
That makes it possible for the secondary pipe to be guided suitably from one end housing to the other without the risk of deformation or deterioration of the interior structure of the said secondary pipe. Thus, the secondary pipe is not bent excessively, which is important when it comprises tensile armour and/or pressure armour. In other words, and when the secondary pipe is analogous to a flexible pipe, as is the case in the use of abandonment or recovery of a flexible pipe, the secondary pipe is not deformed to a radius of curvature smaller than the minimum bend radius (MBR).